Depends on which part of Japan you are intending to go to. It gets cold and snowy on the North (Hokuriku: Fukui, Toyama, Ishikawa, Niigata prefectures) and North-east (Tohoku) to Hokkaido, but the bigger cities of Tokyo, Kyoto and Osaka which are located on the southern and western side of Honshu are quite OK. I've been living in Kyoto for 10 years, Kyoto where most of the bigger Buddhist organizations and universities are has a reputation of being cold during winter but it does not snow much, maybe 1 to 3x a year.

Contemplating the power of Tathagata's Primal Vow,One sees that no foolish being who encounters it passes by in vain.When a person single-heartedly practices the saying of the Name alone,It brings quickly to fullness and perfection [in that person] the great treasure ocean of true and real virtues.- Shinran Shonin